I only met voles when I moved to NC. I recommend cats and ducks. My cats patrol the gardens hoping for a kill. My first year as a duck owner I found out why I never want to get my fingers too close to their beaks. One morning I found a field mouse dead next to their bowl. It was FLAT. I looked a my Giant Pekin drake and smiled... lovely, they kill mice and snakes!
One of the funniest farm yard arguments here on Dancing Goats Farm, was when I shook out a sheet of plastic that had been forgotten for a week on the ground. Several baby snakes flew out, I yelled and swore and Daisy snatched one out of the air and started running with the 6" snake hanging out of the sides of her beak. Two of the girls took off after her trying to snatch the snake from her bobbing and weaving across the yard. They made a hell of a racket trying to get her to share. Mean while I'm yelling come back there are two more here in the grass. Thankfully Hans did not follow his hens. He called the other girls over and stood guard as they found and ate the other snakes. People had warned me if I put in a small prefab pond for my ducks, I'd have snakes. That day I learned why I'd never seen one.